J.R.R. Tolkien studied Middle English in his 1925 edition of Sir Gawain and the Green Knight.
Tolkien edited the poem with E.V. Gordon, and their edition became an important scholarly resource. Sir Gawain and the Green Knight is a late-fourteenth-century Arthurian romance written in a form of Middle English. Tolkien’s notes and glossary helped readers understand its language, vocabulary, and poetic structure.
This language is different from Old English, the language of works such as Beowulf, although Tolkien studied both extensively. The poem’s alliterative style and dialect also interested him as a philologist. Tolkien later translated Sir Gawain and the Green Knight into modern English, but the original poem itself is a Middle English work.